This study was conducted to investigate the effect of heat stress on the physiology of dairy cows and to detect the relationship between rectal temperature (RT) and respiration rate (RR), heart rate (HR), and plasma concentrations of cortisol, thyroxine, and…
Among milk traits, fat-to-protein ratio (FPR) is considered a potential measure of a cow’s energy status and is one of the selection criteria necessary to improve metabolic stability. Further genetic analyses require an appropriate model that describes the pattern of…
The objective of the current study was to determine the effects of partial replacement of soybean meal with corn gluten meal on lactation performance and nitrogen (N) efficiency in lactating Holstein dairy cows. Nine multiparous lactating cows in mid lactation…
The objective of the study was to determine the effect of the duration of the dry period (DP) on the milk yield and milk composition during the following lactation. Milk performance records of 561 Holstein cows, with a previous DP…
Profitable milk production and genetic improvement in dairy herds depend largely on fertile cows calving annually to initiate a new lactation period. Over the last 30 years, several studies have indicated a decline in the reproductive performance of dairy cows…
An experiment was conducted to assess the effects of body condition score (BCS) at calving and level of feed supplementation during early lactation on the Insulin-like growth Factor-I (IGF-I) and reproductive performance in 72 Holstein cows in a pasture-based system…
To evaluate the effect of different ratios of non-fibre carbohydrates (NFC) to rumen degradable protein (RDP) on lactation responses, digestion and dry matter intake (DMI), nine multiparous mid-lactation Holstein cows, averaging 171 ±17 days in milk and 24.1 ± 3.3…
Sixty high-producing multiparous Holstein cows were used in a randomized complete block design experiment to determine the effect of a direct-fed microbial (DFM), Megasphaera elsdenii NCIMB 41125 (Me), on dairy cattle productivity and health. The cows received one of two…
Milk samples collected for analysis in the South African Milk Recording Scheme are routinely preserved by the addition of potassium dichromate. The influence of this preservative, the duration of storage temperatures (O °C or room temperature) and effect of temperature…
The determination of a rate constant for the outflow of chromium-mordanted protein particles from the rumen of lactating dairy cattle. Lactating Friesian/Holstein cows were used for the determination of the outflow rate of protein particles from the rumen. Fishmeal was…
The use of a mathematical programming model for determining optimal nutritional strategy for a dairy cow is described. Mixed Integer Programming (MIP) may be used to fit curvilinear functions, such as the changes in the nutrient requirements of the cow,…
Milk progesterone levels were measured on a daily basis for 44 dairy cows from calving to conception in order to use the progesterone profiles in diagnosing and treating reproductive disorders related to the oestrous cycle. Some of the profiles could…
Two trials were conducted to determine the milk production response to feeding a highly saturated free fatty acid supplement to grazed dairy cows in early lactation. The trials were conducted during spring and autumn, respectively. Sixty-five Friesian cows were supplemented…
A dose-response trial was conducted with dairy cows on six farms in the Ixopo district of the Midlands of KwaZulu-Natal. Up to 30 cows per farm received a single subcutaneous injection of 5 mL of a long-acting/slow-releasing selenium (Se) supplement…
Six ruminally-cannulated cows were assigned to a 2 x 3 changeover experiment with two periods to determine the effect of supplemental biotin on in vitro fibre fermentation kinetics. All the cows received the same basal diet but with different biotin…
The effect of heat processing on ruminal degradation, intestinal digestibility (UDP-D) and absorbable amino acid (AA) profile of cottonseed oilcake (CSOC) and soybean oilcake (SBOC) was calculated. CSOC and SBOC were roasted in a drum roaster at six temperature settings…
The production performance of primiparous Holstein Friesland and Jersey cows wascompared under local conditions during summer. A complete diet providing 15% crude protein (CP), 13% crude fiber (CF) and 10.8 MJ ME/kg dry matter (DM) was fed twice daily on…
In mild climatic regions, open camp systems (dry lots) may be used for dairy cattle. These have a lower capital investment cost than intensive housing systems although the management of open camps is more difficult. The effect of (a) an…
Kikuyu pasture (Pennisetum clandestinum) was evaluated as forage for milk production during the 1985/86 and 1986/87 grazing seasons at the Bathurst Research Station in the seaboard area of the Eastern Cape. The effect of different rotational grazing cycle lengths on…
